Devices, systems, and methods to fixate tissue within the regions of body, such as the pharyngeal conduit

ABSTRACT

Devices, systems and methods develop pressure forces to fixate or brace tissue in targeted pharyngeal structures and individual anatomic components within the pharyngeal conduit.

RELATED APPLICATIONS

This application is a division of co-pending patent application Ser. No.12/148,175 filed 17 Apr. 2008, which is a division of U.S. patentapplication Ser. No. 10/718,254, filed on 20 Nov. 2003, and entitled“Devices, Systems, and Methods to Fixate Tissue within the Regions ofthe Body, such as the Pharyngeal Conduit (now U.S. Pat. No. 7,360,542issued 22 Apr. 2008).”

FIELD OF THE INVENTION

The invention is directed to devices, systems, and methods for thetreatment of sleep disordered breathing including obstructive sleepapnea.

BACKGROUND OF THE INVENTION I. The Characteristics of Sleep Apnea

First described in 1965, sleep apnea is a breathing disordercharacterized by brief interruptions (10 seconds or more) of breathingduring sleep. Sleep apnea is a common but serious, potentiallylife-threatening condition, affecting as many as 18 million Americans.

There are two types of sleep apnea: central and obstructive. Centralsleep apnea, which is relatively rare, occurs when the brain fails tosend the appropriate signal to the breathing muscles to initiaterespirations, e.g., as a result of brain stem injury or damage.Mechanical ventilation is the only treatment available to ensurecontinued breathing.

Obstructive sleep apnea (OSA) is far more common. It is one of theseveral entities that make up the broader group of sleep disorderedbreathing (SDB). This group of disorders ranges from habitual snoring toOSA. Normally, the muscles of the upper part of the throat keep theairway open to permit air flow into the lungs. When the muscles of theupper airway relax and sag, the relaxed tissues may vibrate as air flowspast the tissues during breathing, resulting in snoring. Snoring affectsabout half of men and 25 percent of women—most of whom are age 50 orolder.

In more serious cases, the airway becomes blocked, making breathinglabored and noisy, or even stopping it altogether. In a given night, thenumber of involuntary breathing pauses or “apneic events” can be quitefrequent. These breathing pauses are almost always accompanied bysnoring between apnea episodes, although not everyone who snores hasOSA.

Lack of air intake into the lungs results in lower levels of oxygen andincreased levels of carbon dioxide in the blood. The altered levels ofoxygen and carbon dioxide alert the brain to resume breathing and causearousal. The frequent interruptions of deep, restorative sleep oftenlead to early morning headaches, excessive daytime sleepiness,depression, irritability, and learning and memory difficulties.

The medical community has become aware of the increased incidence ofheart attacks, hypertension and strokes in people with moderate orsevere obstructive sleep apnea. It is estimated that up to 50 percent ofsleep apnea patients have high blood pressure.

Upon an apneic event, the sleeping person is unable to continue normalrespiratory function and the level of oxygen saturation in the blood isreduced. The brain will sense the condition and cause the sleeper tostruggle and gasp for air. Breathing will then resume, often followed bycontinued apneic events. There are potentially damaging effects to theheart and blood vessels due to abrupt compensatory swings in bloodpressure. Upon each event, the sleeping person will be partially arousedfrom sleep, resulting in a greatly reduced quality of sleep andassociated daytime fatigue.

Although some apneic events are normal in all humans, the frequency ofblockages will determine the seriousness of the disease and opportunityfor health damage. When the incidence of blockage is frequent,corrective action should be taken.

II. Sleep and the Anatomy of the Upper Airway

As FIGS. 1A and 1B show, the upper airway consists of a conduit thatbegins at the nasal valve, situated in the tip of the nose, and extendsto the larynx. Although all tissue along this conduit is dynamic andresponsive to the respiratory cycle, only the pharyngeal conduitstructures—the tissues in the region of the airway that starts behindthe nasal cavity and ends in its connections to the supraglotticlarynx—is totally collapsible. The pharyngeal structures and individualanatomic components within this region include the pharyngeal walls; thebase of the tongue; the vallecula; the hyoid bone and its attachments;the soft palate with uvula, the palatine tonsils with associated pillartissue; and the epiglottis.

The cross sectional area of the upper airway varies with the phases ofthe respiratory cycle. At the initiation of inspiration (Phase I), theairway begins to dilate and then to remain relatively constant throughthe remainder of inspiration (Phase II). At the onset of expiration(Phase III) the airway begins to enlarge, reaching maximum diameter andthen diminishing in size so that at the end of expiration (Phase IV), itis at its narrowest, corresponding to the time when the upper airwaydilator muscles are least active, and positive intraluminal pressure islowest. The upper airway, therefore, has the greatest potential forcollapse and closure at end-expiration. Schwab R J, Goldberg A N. UpperAirway Assessment: Radiographic and other Imaging Techniques.Otolaryngol Clin North Am 1998; 31:931-968.

Sleep is characterized by a reduction in upper airway dilator muscleactivity. For the individual with obstructive sleep apnea (OSA) andperhaps the other disorders which comprise much of the group of entitiescalled obstructive sleep-disordered breathing (SDB), it is believed thatthis change in muscle function causes pharyngeal narrowing and collapse.Two possible etiologies for this phenomenon in OSA patients have beentheorized. One is that these individuals reduce the airway dilatormuscle tone more than non-apneics during sleep (the neural theory). Theother is that all individuals experience the same reduction in dilatoractivity in sleep, but that the apneic has a pharynx that isstructurally less stable (the anatomic theory). Both theories may infact be contributors to OSA, but current studies seem to support thatOSA patients have an intrinsically structurally narrowed and morecollapsible pharynx. Isono S. Remmers J, Tanaka A Sho Y, Sato J, NishinoT. Anatomy of Pharynx in Patients with Obstructive Sleep Apnea and inNormal Subjects. J Appl Physiol 1997: 82:1319-1326.

Although anatomic closure is often accentuated at specific sites, suchas the velopharyngeal level [Isono, Ibid], studies of closing pressures[Isono, Ibid] supports dynamic fast MRI imaging that shows narrowing andcollapse usually occurs along the entire length of the pharynx. ShellockF G, Schatz C J, Julien P, Silverman J M, Steinberg F, Foo T K F, Hopp ML, Westbrook P R. Occlusion and Narrowing of the Pharyngeal Airway inObstructive Sleep Apnea: Evaluation by Ultrafast Spoiled GRASS MRImaging. Am J of Roentgenology 1992:158:1019-1024.

III. Prior Treatment Modalities

To date, the only modality that addresses collapse along the entireupper airway is mechanical positive pressure breathing devices, such ascontinuous positive airway pressure (CPAP) machines. All othermodalities, such as various surgical procedures and oral appliances, bytheir nature, address specific sectors of the airway (such as palate,tongue base and hyoid-vallecula levels), but leave portions ofpharyngeal wall untreated. This may account for the considerably highersuccess rate of CPAP over surgery and appliances in controlling OSA.Although CPAP, which in essence acts as an airway splint for therespiratory cycle, is highly successful, it has some very significantshortcomings. It can be cumbersome to wear and travel with, difficult toaccept on a social level, and not tolerated by many (for reasons such asclaustrophobia, facial and nasal mask pressure sores, airwayirritation). These factors have lead to a relatively poor long-termcompliance rate. One study has shown that 65% of patients abandon theirCPAP treatment in 6 months.

The need remains for simple, cost-effective devices, systems, andmethods for reducing or preventing sleep disordered breathing events.

SUMMARY OF THE INVENTION

One aspect of the invention provides devices, systems, and methods thatbrace or fixate tissue in targeted pharyngeal structures and/orindividual anatomic components within the pharyngeal conduit by use of apressure chamber, which is sized and configured to be located outside ofthe pharyngeal conduit and to hold a pressure that is less thanatmospheric pressure. In one embodiment, the pressure chamber is sizedand configured to hold a pressure that is less than a minimum pressurecondition experienced in the pharyngeal conduit during a respirationcycle. The pressure chamber can be sized and configured, e.g., to beworn about a neck.

The devices, systems, and methods can be used to treat airway collapseand increased airway resistance associated with the entire spectrum ofobstructive sleep-disordered breathing. The devices, systems, andmethods can also be used to lend upper airway support in neurologicalassociated dystonic disorders.

Other features and advantages of the invention shall be apparent basedupon the accompanying description, drawings, and claims.

DESCRIPTION OF THE DRAWINGS

FIGS. 1A and 1B are anatomic views of the upper airway in a human,showing certain pharyngeal structures and individual anatomic componentswithin the pharyngeal conduit, FIG. 1A comprising a lateral view andFIG. 1B is a superior view taken generally along line 1B-1B in FIG. 1.

FIG. 2A shows in a diagrammatic way a system that uses pressure tofixate or brace tissue along the pharyngeal conduit.

FIGS. 3A and 3B show a pressure chamber system of a type shown in FIG.2.

DETAILED DESCRIPTION

Although the disclosure hereof is detailed and exact to enable thoseskilled in the art to practice the invention, the physical embodimentsherein disclosed merely exemplify the invention, which may be embodiedin other specific structure. While the preferred embodiment has beendescribed, the details may be changed without departing from theinvention, which is defined by the claims.

I. Systems to Fixate or Brace Tissue

A. Pressure Chamber Systems

FIG. 2 shows in a diagrammatic way a pressure chamber system 14 that, inuse, fixates or braces tissue in targeted pharyngeal structures andindividual anatomic components within the pharyngeal conduit by alteringthe differential between internal pressure existing within thepharyngeal conduit (P1 in FIG. 2) and external pressure existing outsidethe pharyngeal conduit (P2 in FIG. 2). More particularly, the pressurechamber system 14 lowers, in a localized region surrounding all or aportion of the pharyngeal conduit, the external pressure to a pressurecondition (P2) that is less than atmospheric pressure and desirably lessthan the minimum expected pharyngeal pressure (P1), which typicallyoccurs during the inhalation phase of the respiratory cycle. Thepressure chamber system 14 desirably creates in this localized region apressure differential that impedes tissue collapse to maintain patencyof the conduit. The purpose of the pressure chamber system 14 is todesirably nullify the vector sum of the extralumenal forces on theconduit, to make it de-compressive. These forces are created byatmospheric pressure, gravity, contractive forces caused by upper airwaymuscle activity, and inward forces caused by subatmospheric luminalpressure generated during inhalation.

Like the force system 10, the pressure chamber system 14 can be used totreat airway collapse and increased airway resistance associated withthe entire spectrum of obstructive sleep-disordered breathing. Thepressure chamber system 14 can also be used to lend upper airway supportin neurological associated dystonic disorders.

In one basic form, the pressure chamber system 14 comprises at least oneexternal pressure chamber 16 (shown in FIG. 2), which is sized andconfigured to be worn by an individual, when desired, about a targetedtissue region or regions within the pharyngeal conduit. The targetedpharyngeal structures and individual anatomic components within thisregion can include the pharyngeal walls; the base of the tongue; thevallecula; the soft palate with uvula; the palatine tonsils withassociated pillar tissue; and the epiglottis.

The pressure chamber 16 establishes a localized pressure condition (P2)about the targeted tissue region that is less than atmospheric pressureand desirably less than the minimum-expected pressure condition presentin the pharyngeal conduit (P1). Exposed to a localized pressuredifferential that is more negative than ambient conditions, tissue alongthe pharyngeal conduit resists collapse when collapse is imminent, i.e.,upon inhalation during sleep. The pressure chamber 16 can be removedduring waking hours.

Illustrative embodiments of implanted force systems 10 and externalpressure chamber systems 14 will now be described.

II. Illustrative Structures Useable with the Pressure Chamber System

FIGS. 3A and 3B show an illustrative embodiment of a pressure chambersystem 14. The system 14 includes a collar 74 that is sized andconfigured to be removably worn about the neck of an individual when thedesired physiologic effect is desired, e.g., during sleep (as FIG. 3Ashows).

The collar 74 carries a pressure-retaining chamber 16. When the collar74 is worn, the chamber 16 encircles all or a portion of the pharyngealconduit (see FIG. 3B). The chamber 16 may comprise an elastic materialfor comfort.

An air pump 76 has an inlet that communicates with the chamber 16 and anoutlet that communicates with the ambient environment. The air pump 76can be carried by the collar 74 (as shown), or it can be located remotefrom the collar, e.g., bedside, and coupled by tubing to the air chamber16. The air pump 76 can comprise, e.g., a diaphragm pumping mechanism,or a reciprocating piston mechanism, or a centrifugal (turbine)air-moving mechanism.

The air pump 76 may be manually operated, or a power source 78 may drivethe air pump 76. The power source 78 can be, e.g., an electric motorthat can be plugged into a conventional electrical receptacle, or bebattery-powered, or both (in which case the battery can berechargeable). When driven, the air pump 76 draws air from the chamber16, to establish within the chamber 16 a pressure condition that is lessthan atmospheric.

A regulator 80 may be coupled to govern operation of the air pump 76 toestablish and maintain a desired sub-atmospheric pressure conditionwithin the chamber 16. The desired pressure condition is selected to beless than atmospheric pressure and is desirably less the minimumpressure condition expected experienced in the pharyngeal conduit, whichis typically encountered during the inhalation phase of the respirationcycle. The pressure selected desirably nullifies the vector sum of theextralumenal forces, which are created by the interaction of atmosphericpressure, gravity, the contractive forces within the tissue due to upperairway muscle activity, and the inward forces generated bysubatmospheric luminal pressure generated during inhalation. It isbelieved that the pressure condition established within the chamber 16should be at least −1 cm H₂O and desirable at least −10 cm H₂O. Thepressure created by the system 14 desirably also takes into accountdifferent anatomical structural differences of individual airways.

The system 14 can also include some form of physiologic feedback controlfor the air pump. In this arrangement, the system includes a monitor orsensor 82 to sense fluctuations of pharyngeal pressure during therespiration cycle. When the pharyngeal pressure meets or exceeds aselected threshold minimum pressure, the monitor 82 sends a controlsignal to the pump 76, to activate the pump 76. The pump 76, whenactivated, operates to maintain a desired pressure condition within thechamber 16 while sensed pharyngeal pressure is below the threshold. Thepump 76, when activated, could also operate to maintain a desiredpressured differential between pressure in the chamber 16 and the sensedpharyngeal pressure while sensed pharyngeal pressure is below thethreshold. Once pharyngeal pressure exceeds the threshold, the monitor82 sends a control signal to deactivate the pump 76. In this way, thesystem 14 conditions tissue to resist collapse when respiratoryconditions are most conducive to collapse, but otherwise does not affectthe tissue morphology and/or motility and/or shape. The pressure chamber16 can also serve to reduce tissue vibration and be used in thetreatment of snoring.

Other forms of physiologic feedback control can be used. For example,airflow can be measured during the respiratory cycle, and/or theexpansion/contraction of the chest can be monitored during the cycle.Chamber pressure can be varied to response to requirements dictated bythe respiratory cycle.

The above-described embodiments of this invention are merely descriptiveof its principles and are not to be limited. The scope of this inventioninstead shall be determined from the scope of the following claims,including their equivalents.

1. An Apparatus to brace or fixate tissue in targeted pharyngealstructures and/or individual anatomic components within the pharyngealconduit comprising a chamber sized and configured to be located outsideof the pharyngeal conduit and to hold a pressure that is less thanatmospheric pressure.
 2. An apparatus according to claim 1, comprising amonitor or sensor to sense fluctuations of pharyngeal pressure during arespiration cycle.
 3. An apparatus according to claim 1, wherein thechamber is sized and configured to hold a pressure that is less than aminimum pressure condition experienced in the pharyngeal conduit duringa respiration cycle.
 4. An apparatus according to claim 1, wherein thechamber is sized and configured to be worn about a neck.
 5. A method ofbrace or fixate tissue in targeted pharyngeal structures and/orindividual anatomic components within the pharyngeal conduit comprisingthe steps of providing an apparatus as defined in claim 1, and locatingthe apparatus outside the pharyngeal conduit.